Employee Benefit Plans (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Accrued expenses		$ (45)		$ (37)
Other long-term liabilities		(878)		(834)
Pension Plans [Member]
Changes in benefit obligation
Benefit obligation as of beginning of year		3,239	[1]	2,639
Service cost		140		119		$ 133
Interest cost		85		98		91
Participant contributions		0		0
Benefits paid		(195)		(154)
Actuarial loss		339		528
Other		17		9
Benefit obligation as of end of year		3,625	[1]	3,239	[1]	2,639
Changes in plan assets
Fair value of plan assets as of beginning of year	[1]	2,709		2,236
Actual return on plan assets	[1]	413		490
Valero contributions	[1]	129		128
Participant contributions	[1]	0		0
Benefits paid	[1]	(195)		(154)
Other	[1]	11		9
Fair value of plan assets as of end of year	[1]	3,067		2,709		$ 2,236
Reconciliation of funded status:
Funded status as of end of year	[1]	(558)		(530)
Accumulated benefit obligation		3,398		3,039
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		7		5
Accrued expenses		(24)		(17)
Other long-term liabilities		(541)		(518)
Amounts recognized in balance sheet for defined benefit plans		$ (558)		$ (530)
Actuarial Gain (Loss), Discount Rates (Textual)
Discount rate		2.62%		3.14%		4.25%
Other Postretirement Benefit Plans [Member]
Changes in benefit obligation
Benefit obligation as of beginning of year		$ 336	[1]	$ 292
Service cost		6		5		$ 6
Interest cost		9		11		10
Participant contributions		12		11
Benefits paid		(28)		(29)
Actuarial loss		23		41
Other		0		5
Benefit obligation as of end of year		358	[1]	336	[1]	292
Changes in plan assets
Fair value of plan assets as of beginning of year	[1]	0		0
Actual return on plan assets	[1]	0		0
Valero contributions	[1]	16		18
Participant contributions	[1]	12		11
Benefits paid	[1]	(28)		(29)
Other	[1]	0		0
Fair value of plan assets as of end of year	[1]	0		0		$ 0
Reconciliation of funded status:
Funded status as of end of year	[1]	(358)		(336)
Defined Benefit Plan, Amounts Recognized in Balance Sheet
Deferred charges and other assets, net		0		0
Accrued expenses		(21)		(20)
Other long-term liabilities		(337)		(316)
Amounts recognized in balance sheet for defined benefit plans		$ (358)		$ (336)
Actuarial Gain (Loss), Discount Rates (Textual)
Discount rate		2.64%		3.32%

[1] Plan assets include only the assets associated with pension plans subject to legal minimum funding standards. Plan assets associated with U.S. nonqualified pension plans are not included here because they are not protected from our creditors and therefore cannot be reflected as a reduction from our obligations under the pension plans. As a result, the reconciliation of funded status does not reflect the effect of plan assets that exist for all of our defined benefit plans. See Note 20 for the assets associated with certain U.S. nonqualified pension plans.